50 lines
1.6 KiB
Markdown
50 lines
1.6 KiB
Markdown
# Computer
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## Summary
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1. [Aims and challenges](#aims-and-challenges)
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2. [Architecture choices](#architecture-choices)
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3. [Design](#design)
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1. [The instruction set.](#the-instruction-set)
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## Aims and challenges
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Make a turing complete computer from scratch.
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The computer will be composed of :
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- A CPU
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- Some RAM
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- Some ROM
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At first every part will be the "industrial" version :
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- The CPU from logic gates.
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- The RAM a [SRAM](https://en.wikipedia.org/wiki/Static_random-access_memory) chip (*[UM61256BK-20](/Documents/UM61256.pdf) from 1993*)
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- The ROM another chip (*[D27C010](/Documents/D27C010-200V10.pdf) from 1986 !*)
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Then the aim is to replace them with made from scratch versions.
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For the moment only the RAM is meant to be replaced with homemade magnetic core RAM.
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## Architecture choices
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The computer will be in 8 bits since the RAM and ROM are meant to be in 8 bits.
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The CPU will have ports for inputs / outputs.
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## Design
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The design is inspired of great people hard work :
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- [Ben Eater's 8 bits breadboard computer](https://eater.net/8bit)
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- [Mattbatwings's minecraft computer tutorial](https://youtu.be/hAZEXqWLTmY?si=qgic0b28PMeOPs_l)
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### The instruction set.
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Every instruction is 8 bits long. And there is 3 bytes of data after the instruction.
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Because the ROM is 8 bits, every instruction will take 4 bytes.
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This property might help for [instruction pipelining](https://en.wikipedia.org/wiki/Instruction_pipelining) in the future.
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These are only real instructions. Pseudoinstruction will be defined later.
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| Mnemonic | Description | Pseudocode |
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| :-------: | :------------ | :------------ |
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